The Hikikomori Diagnostic Evaluation (<scp>HiDE</scp>): a proposal for a structured assessment of pathological social withdrawal
Authors: Alan R. Teo, Kazumasa Horie, Keita Kurahara, Takahiro A. Kato
Journal: World Psychiatry (2023)

Our social ties underpin the substance of our daily lives and exert a strong influence on our individual mental health and collective well-being. While these connections often imbue our lives with meaning and positive feelings, they can for some people go terribly awry. One of the more striking manifestations of this is called hikikomori. Hikikomori has been an emerging topic of study in psychiatry since the 1990s, and is characterized by physical isolation in one's home, compounded by significant functional impairment or distress related to this isolation, and a sustained duration of symptoms for at least six months1, 2. While patients with hikikomori require unique consideration, studies spanning the globe have revealed that comorbidity of hikikomori with various other psychiatric disorders, such as autism spectrum disorder and major depressive disorder, is common1. Having conducted research and provided clinical care for individuals with hikikomori for more than 25 years, our group has contributed significantly to the steady growth of popular interest3 and scholarly study of this condition across countries and cultures. To help standardize what is meant by the term "hikikomori", we introduced an updated definition in 20204. More recently, hikikomori has been included in the section "Culture and Psychiatric Diagnosis" of the DSM-5-TR5, presumably because it was first described in Japan. While these have been steps in the right direction, we believe that there is now a pressing need for a transcultural tool which can help clinicians and researchers to understand and assess individuals for hikikomori. Here we introduce a structured diagnostic interview called Hikikomori Diagnostic Evaluation (HiDE), providing a practical guidance on how to collect information and assess individuals for this condition. There is a long history of structured diagnostic interviews in psychiatry, which might lead one to wonder why one is particularly needed for hikikomori. The most obvious reason is that social withdrawal is scarcely considered within existing tools such as the Structured Clinical Interview for DSM-5 (SCID-5), the Composite International Diagnostic Interview (CIDI) and the Mini-International Neuropsychiatric Interview (MINI). Unless reliable and standardized tools are employed in studies purporting to examine hikikomori, advancement of this field of research will be stifled. Furthermore, we regularly encounter well-meaning individuals who seek to self-diagnose (or conversely, rule out) hikikomori by simply filling out the 25-item Hikikomori Questionnaire (HQ-25), a self-report measure of symptoms of hikikomori that we developed to support (but not replace) the process of clinical diagnosis of the condition6, similarly to the current use of other patient-reported measures such as the Patient Health Questionnaire-9 (PHQ-9) or the Generalized Anxiety Disorder-7 (GAD-7). The HiDE is a clinician-administered tool that requires 5 to 20 min to complete, depending on the number of positive responses (see supplementary information for the full structured diagnostic interview form). We originally developed it for use in our research. Over the past two years, applying it to over 100 patients seen in our academic medical center clinic in Japan, we have continued to refine it. To minimize recall bias, most items in the HiDE focus on symptomatology during the past month. The first section of the tool addresses the essential features required to establish a diagnosis of hikikomori. Items quantify the frequency of outings, the chronicity of social withdrawal, and the distress and functional impairment related to this withdrawal. We have found that some patients with hikikomori overemphasize non-social, brief outings (e.g., putting out the trash) as evidence of going outside the home, and we therefore carefully characterize the purpose and duration of outings. We have also found patients who deny distress or functional impairment, though they acknowledge significant concern by family members or others about their social withdrawal. For this reason, we incorporate concern by others as evidence of distress or functional impairment. The next section of the tool aims to obtain supplemental details that are not strictly required for the diagnosis but do provide helpful context to patients' social withdrawal. These items cover social participation, including work and school, personal activities and interests, attending appointments for medical care or counseling, and in-person versus other interactions. Specific attention is paid to whether these social interactions rise to the level of having actual conversation, since in our clinical experience some patients (incorrectly) insist that exchanging greetings qualifies for meaningful social interaction. Clinicians or researchers who lack the time to administer the HiDE to all patients may consider using a screening form that we have also developed (see supplementary information). We suggest that the full HiDE be administered to patients who respond that: a) they spend out of their home one hour or less per day at least three days a week, and b) they personally feel bothered by this, or their family or others they know feel bothered by this. It would also be reasonable for patients with a positive screen to complete the HQ-25 in order to provide supporting information on the severity of their symptoms of hikikomori. The HiDE has proven an indispensable tool for the structured assessment of pathological social withdrawal in our clinical practice and ongoing research. However, we fully recognize the need for further empirical study of the tool to determine its validity and implications beyond our practice. We hereby call upon our colleagues around the globe to help assess its reliability and validity in their practice settings, examine aspects of its implementation (e.g., feasibility, acceptability, appropriateness, and clinical utility), and help refine the tool as appropriate. A collective effort in this direction will help move hikikomori into the mainstream of diagnostic assessment in psychiatry.